Without knowing your shooting preferences and style it's a hard question to respond to. In case you look for something longer than the 23mm (35mm FF equiv.), the 35, 50 or 56 are all great lenses. Depends on how much longer you need. The 56 has by the way the same filter thread as the 23 which can be convenient. If you really need 'long' then the 55-200 or the 50-140 are good additions that won't make your 23 redundant. The 50-140 however is well-over $1000, but you can look at used ones.
In case you want something wider, the 16 or even better the 14 or the 12mm Zeiss are great additions to your 23. Esp. the 14 pairs nicely since it has the same manual focus clutch as the 23 (in case you focus manually at all). The 16/f1.4 also has that, but might be too close in focal length to the 23.
As for zoom lenses, I guess you bought the 23 for a reason. The issue with buying a standard zoom next to it (like the 16-55 or the 18-55) is that you probably leave that on and might not use the 23 that much anymore. That is a pity since in terms of IQ it is one of Fuji's best lenses. Adding the 10-24 (which is on sale) is perhaps a better alternative as the long end (24) of that lens isn't the best part of that lens, which keeps the 23 a good extension.